Electrolytic cell stacks which are regenerative, that is to say which can be operated in an electrolysis mode to produce hydrogen and oxygen, and also in a fuel cell mode to produce electricity and water, can be used in earth orbiting satellites in place of high energy rechargeable batteries. Such a regenerative stack can be operated in its fuel cell mode to produce electricity to power the on-board satellite systems during such times as the satellite has no access to sunlight. During periods when the satellite is exposed to sunlight, solar panels on the satellite will produce electricity to operate the on-board electrical systems, and also to operate the stack in its electrolysis mode. When operating in the electrolysis mode, the stack produces hydrogen and oxygen which are stored for later consumption by the stack when operating in the fuel cell mode. When operating in the electrolysis mode, the stack uses up water which is produced in the previous fuel cell operating mode. In order that the water needed in the electrolysis mode can be provided without any mechanical pumps or the like, the stack will be made up of two types of cells, one of which is an electrolysis cell, and the other of which is a fuel cell. The stack will be formed with the cell types adjacent to each other so that water formed by the fuel cell mode of operation can migrate into the electrolysis cells during the electrolysis mode of operation to be consumed. This type of stack is disclosed in an Air Force Aero Propulsion Laboratory Report, Air Force Systems Command, Wright Patterson Air Force Base dated September, 1973. This report is entitled "Dual Cell Regenerative Fuel Cell Follow-On Investigation" and was authored by J. K. Stedman and D. B. Baillieul. This prior art design, even though operating in a static or passive manner, is structurally complex in that it includes the use of a bellows to equalize oxygen and hydrogen pressures; requires a separate hydrogen tank inside of the stack; and uses semi-cylindrical cell plates which are difficult to manufacture and form into a stack.